Re: [Qemu-arm] [Qemu-devel] [PATCH] hw/arm/virt: Reject gic-version=host for non-KVM

["Richard W.M. Jones" <rjones@redhat.com>]

On Fri, Jun 17, 2016 at 05:31:20PM +0100, Peter Maydell wrote:
> On 17 June 2016 at 17:10, Richard W.M. Jones <rjones@redhat.com> wrote:
> > On Fri, Jun 17, 2016 at 03:49:38PM +0100, Peter Maydell wrote:
> >> > I agree that we really need to do better here (thinking about
> >> > the problem is on my todo list but generally other more pressing
> >> > issues intervene). I'd welcome suggestions for semantics which
> >> > (a) do what you want (b) are reasonably in line with what we do
> >> > on other host architectures (c) don't break existing command lines.
> >> > (I think those are the main requirements.)
> >>
> >> ...so does anybody have any concrete suggestions? We could fix
> >> this for 2.7 but we're starting to run low on time for that.
> >
> > I have changed libguestfs so it tries to guess if KVM will be used or
> > not.  We have to do this for the -cpu option too, but the guess is not
> > too reliable.  Only QEMU has the actual knowledge we need.
> >
> > https://github.com/libguestfs/libguestfs/commit/7023f20830a681ef36f8f99415fe41791555a3db
> >
> > Can we not have a "give me a GIC which will work" option, eg.
> >
> >   -M virt,gic-version=besteffort,accel=kvm:tcg
> >
> > I don't care if it's not the fastest or most featureful.
> 
> Do we also not care if the result is not consistent
> between versions of QEMU? (eg if you go from 2.6 to
> 2.7 does it have to stay doing the same thing it
> always did?)

For libguestfs, no, since we don't do any migration or saving the
state of the VM.

Rich.

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